1. Technical Field
The present invention relates to a seat belt retractor and to a method of making a seat belt retractor, and in particular relates to a seat belt retractor and a method of making a seat belt retractor having a frame, a spool supported in the frame for rotation in belt winding and unwinding directions, and a spring biasing the spool in the belt winding direction.
2. Background Art
Many different seat belt retractors are known. Typically, a seat belt retractor includes a generally U-shaped frame and a spool rotatably mounted between the two legs of the U-shaped frame. Belt webbing is wound on the spool. The spool is rotatable in a belt withdrawal direction to pay out belt webbing and in a belt retraction direction to wind belt webbing onto the spool.
A belt webbing guide is fixedly connected to the U-shaped frame. The belt webbing guide and the U-shaped frame define an opening through which the belt webbing extends. A tie bar is sometimes connected between the two legs of the U-shaped frame to provide additional support for the U-shaped frame. A coil spring is located adjacent one leg of the U-shaped frame and is operatively connected to one end of the spool for biasing the spool in the belt retraction direction. A spring cover extends over the coil spring and is fastened to the adjacent leg of the U-shaped frame to cover and protect the coil spring.
A sensor mechanism, such as a vehicle deceleration sensor and/or a webbing acceleration sensor, may be located adjacent the other leg of the U-shaped frame. A vehicle deceleration sensor senses vehicle deceleration of at least a predetermined magnitude. A webbing acceleration sensor senses acceleration of the belt webbing in the belt withdrawal direction of at least a predetermined amount. A sensor cover extends over the sensor mechanism and is fastened to the adjacent leg of the U-shaped frame to cover and protect the sensor mechanism. An actuatable locking pawl arrangement is operatively connected to the spool for, when actuated, preventing rotation of the spool in the belt withdrawal direction. The locking pawl arrangement actuates in response to the sensor sensing vehicle deceleration of at least the predetermined magnitude and/or acceleration of the belt webbing in the belt withdrawal direction of at least a predetermined amount.
The known seat belt retractors have a relatively large number of separate components. When a seat belt retractor has a relatively large number of separate components, the amount of labor required to assemble the seat belt retractor is relatively large, resulting in relatively high manufacturing costs.